The present invention relates to an apparatus for joining sheets or panels in the assembly and construction of a combination "expanded" construction for the make-up of packages and containers utilized for enclosing articles of commerce. The sheets or panels may be fabricated of fiber board, paper board, or other materials such as plastic or thin sheet metal. There is at present one generally accepted method for joining flat sheets of material in the production of a panel that is greater in dimension than the sheets employed in the make-up of the panel. This is referred to usually as "corrugated board stock" and is made of coarse fiber kraft material referred to in the trade as "liner board." Normally, the mechanical adjoinment of corrugated board is accomplished by the formation of an internal sheet in alternate involute forms or corrugations that are lateral to the make-up of the web or paper board sheets in assembly of such a combination. The product that results is a laminate of three or more board sheets consisting of a center corrugation joined by two flat sheets attached with adhesives to the apex of each corrugation. This material exhibits rigidity in one direction parallel to the course of the corrugation form and is flexible in a direction at right angles to these convolutions.
This invention teaches a method of achieving a mechanical interlock between two paper board panels through the adhesive attachement of extended latching elements, area tabs or partially perforated components which are bent at right angles to the planes of the perforated panels to afford an extension or intermediate linkage functioning to connect two such parallel panels or sheets to one another.
The production of the board of the present invention achieves a reduction in the amount of paper board or fiber board required in the manufacturing of an expanded board configuration and produces a board having rigidity in two directions and exhibiting tension and compression strength comparable to that of a prior art corrugated board consisting of three sheets. For purposes of full enclosure, the nature of the perforated configuration employed in each panel requires that an overlay sheet of light weight material be attached to the face of at least one such panel to dress or finish the external surface of a package. A similar overlay sheet can be applied to the opposite face of the board for dress or added strength.
In general usage, containers of the type produced with corrugated material fall into the category of shipping boxes and tertiary units that are employed for the utilitarian function of transportation.
Fiber board forms of corrugated material are regulated by certain rules that apply to shipments in interstate commerce. It is the intent and the purpose of this invention to make possible the strength and utility associated with conventional corrugated board, by utilizing materials with lighter basis weight and consisting of less fiber product than is the case presently with corrugated board stock.
It is an object of this invention to produce a paper board or fiber board product with a width dimension greater than the sum of thicknesses of the panels employed in the combination, by producing numerous extensions or tabs perforated from the panels and by attaching these tabs by adhesive means one to another.
It is a further object of this invention to employ in the production of a board with such an increased dimensional thickness, an area tab intermediary, partially perforated from the panels used and containing a secondary performation deployed within an opening in the tab of the opposite panel to achieve a mechanical linkage without requirement of adhesives.
It is a further object of this invention to produce a product that exhibits physical improvement in tension and compression over that exhibited by corrugated board and to accomplish this improvement by the specific displacement, in a varied angular arrangement, of partially perforated area tabs, and attaching said tabs to other tabs identically displaced from an opposite panel member.
It is a further object of this invention to provide a fiber board combination that consists of three sheets, one of which encloses one external perforated face of the product of this invention to provide an external finish to a container or box utilizing this medium.
It is an additional object of this invention to provide two panels of light weight sheet, fiber board material, to cover or enclose both sides of the perforated area of the product in this invention to achieve a finished packaging material.
It is another object of this invention to provide additional strength in this combination by the specific placement of the uncut portion of the perforation, thus making the tab join the coinciding tab element of the opposite sheet in a common plane but varying the angular placement of the tab planes from perforation to perforation.
It is a further object of this invention to provide an apparatus for the final closing or assembly of the board of the present invention which consists of means to compress the area tabs of the two panels together to accomplish a bonding function and, while under this pressure, is operative to move the pressure means in a counterrotational direction across the backs of the two tabs to distribute the adhesive disposed between their adjoined faces, thus improving the bonding of this intermediary linkage.
An additional object of this invention is the production of a paper board product of novel configuration in panels utilizing extremely heavy paper board materials in the order of 1/16th to 1/4 of an inch in thickness.
It is an additional object of this invention to provide improved procedures for the production of the novel paper board product of the present invention that involve web handling machinery and continuous procedures in the form of rotary equipment, cylinders and the like, making possible large volume manufacturing of the product, usually employing paper gauges ranging from 0.005 to 0.905 inches.
A further object of this invention is to provide a novel geometry in the enjoinment of paper and fiber board components to accommodate the necessary drying of adhesives by facilitating the passage of air through the plane of the board during the manufacturing process.
It is another object of this invention to produce a board configuration that permits the passage of air through its structure for the packing of items that require ventilation.